foo.cc: In function 'int main()':
foo.cc:26:6: warning: unused variable 'k' [-Wunused-variable]
  int k=0;
      ^
foo.cc:27:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&a,&b);
  ~~~~~^~~~~~~~~~~~~~

正在同步测试数据，请稍后
自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。